Ctrl+P→手前のUnreadチャンネル、Ctrl+N→次のUnreadチャンネルに移動

private.xml

<?xml version="1.0"?>
<root>
    <appdef>
        <appname>SLACK</appname>
        <equal>com.tinyspeck.slackmacgap</equal>
    </appdef>
    <item>
        <name>For Slack CTRL+N=move previous unread hannel, CTRL+P=move unread next channel</name>
        <identifier>private.app_slack_move_channel_with_altn_altp</identifier>
        <only>SLACK</only>
        <autogen>__KeyToKey__ KeyCode::N, ModifierFlag::CONTROL_L, KeyCode::CURSOR_DOWN, ModifierFlag::OPTION_L, ModifierFlag::SHIFT_L</autogen>
        <autogen>__KeyToKey__ KeyCode::P, ModifierFlag::CONTROL_L, KeyCode::CURSOR_UP, ModifierFlag::OPTION_L, ModifierFlag::SHIFT_L</autogen>
    </item>
</root>

@see http://blog.glidenote.com/blog/2014/08/06/custom-keybind-for-slack/